131 lines
5.5 KiB
Plaintext
131 lines
5.5 KiB
Plaintext
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Metadata-Version: 1.0
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Name: sgp4
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Version: 1.1
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Summary: Track earth satellite TLE orbits using up-to-date 2010 version of SGP4
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Home-page: https://github.com/brandon-rhodes/python-sgp4
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Author: Brandon Rhodes
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Author-email: brandon@rhodesmill.org
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License: MIT
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Description:
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This Python package computes the position and velocity of an
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earth-orbiting satellite, given the satellite's TLE orbital elements
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from a source like `Celestrak <http://celestrak.com/>`_. It implements
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the most recent version of SGP4, and is regularly run against the SGP4
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test suite to make sure that its satellite position predictions **agree
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to within 1 µm** of the predictions of the standard C++ implementation
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of the algorithm. This error is far less than the 1–3 km/day by which
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satellites themselves deviate from the ideal orbits described in TLE
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files.
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The C++ function names have been retained, since users may already be
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familiar with this library in other languages. Here is how to compute
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the x,y,z position and velocity for Vanguard 1 at 12:50:19 on 29
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June 2000:
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>>> from sgp4.earth_gravity import wgs72
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>>> from sgp4.io import twoline2rv
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>>> line1 = ('1 00005U 58002B 00179.78495062 '
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... '.00000023 00000-0 28098-4 0 4753')
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>>> line2 = ('2 00005 34.2682 348.7242 1859667 '
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... '331.7664 19.3264 10.82419157413667')
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>>>
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>>> satellite = twoline2rv(line1, line2, wgs72)
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>>> position, velocity = satellite.propagate(
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... 2000, 6, 29, 12, 50, 19)
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>>>
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>>> position
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[5576.056952400586, -3999.371134576452, -1521.9571594376037]
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>>> velocity
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[4.772627303379319, 5.119817120959591, 4.275553909172126]
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The position vector measures the satellite position in **meters** from
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the center of the earth. The velocity is the rate at which those same
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three parameters are changing, expressed in **meters per second**.
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There are three gravity models available that you can import from the
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``earth_gravity`` module:
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* ``wgs72``
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* ``wgs72old``
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* ``wgs84``
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The ``wgs72`` model seems to be the most commonly used in the satellite
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tracking community, and is probably the model behind most TLE elements
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that are available for download.
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The ``twoline2rv()`` function returns a ``Satellite`` object whose
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attributes carry the data loaded from the TLE entry.
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Most of this class's hundred-plus attributes are intermediate values
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of interest only to the propagation algorithm itself. Here are the
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attributes set by ``sgp4.io.twoline2rv()`` in which users are likely
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to be interested:
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``satnum``
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Unique satellite number given in the TLE file.
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``epochyr``
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Full four-digit year of this element set's epoch moment.
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``epochdays``
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Fractional days into the year of the epoch moment.
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``jdsatepoch``
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Julian date of the epoch (computed from ``epochyr`` and ``epochdays``).
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``ndot``
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First time derivative of the mean motion (ignored by SGP4).
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``nddot``
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Second time derivative of the mean motion (ignored by SGP4).
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``bstar``
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Ballistic drag coefficient B* in inverse earth radii.
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``inclo``
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Inclination in radians.
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``nodeo``
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Right ascension of ascending node in radians.
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``ecco``
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Eccentricity.
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``argpo``
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Argument of perigee in radians.
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``mo``
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Mean anomaly in radians.
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``no``
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Mean motion in radians per minute.
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This implementation passes all of the automated tests in the August 2010
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release of the reference implementation of SGP4 by Vallado et al., who
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originally published their revision of SGP4 in 2006:
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Vallado, David A., Paul Crawford, Richard Hujsak, and T.S. Kelso, “Revisiting Spacetrack Report #3,” presented at the AIAA/AAS Astrodynamics Specialist Conference, Keystone, CO, 2006 August 21–24.
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If you would like to review the paper, it is `available online
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<http://www.celestrak.com/publications/AIAA/2006-6753/>`_. You can
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always download the latest version of their code for comparison against
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this Python module (or other implementations) at `AIAA-2006-6753.zip
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<http://www.celestrak.com/publications/AIAA/2006-6753/AIAA-2006-6753.zip>`_.
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This module was adapted from Vallado's C++ code since its revision date
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was the most recently updated SGP4 implementation in their zip file:
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* C++, August 2010
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* Fortran, August 2008
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* Pascal, August 2008
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* Matlab, May 2008
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* Java, July 2005
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Changelog
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---------
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| 2012-11-22 — 1.1 — Python 3 compatibility; more documentation
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| 2012-08-27 — 1.0 — Initial release
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Platform: UNKNOWN
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Classifier: Development Status :: 5 - Production/Stable
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Classifier: Intended Audience :: Science/Research
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Classifier: License :: OSI Approved :: MIT License
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Classifier: Programming Language :: Python :: 2
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Classifier: Programming Language :: Python :: 2.6
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Classifier: Programming Language :: Python :: 2.7
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Classifier: Programming Language :: Python :: 3
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Classifier: Programming Language :: Python :: 3.1
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Classifier: Programming Language :: Python :: 3.2
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Classifier: Topic :: Scientific/Engineering :: Astronomy
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